I'm not sure about a Compaq...It appears that you are prompted to hit F1 to get into the BIOS setup?
Have you tried tapping the Delete key after pushing the power button?
If F1 is the usual way...I would suggest clearing the CMOS and see if that makes a difference being able to access the BIOS/Setup... If that works, you can change the boot order to A:
Be sure before you put any floppy disk into the drive that you have it write protected...
Are you using NTFS or FAT on WinXP?